Impacts of radiative corrections on measurements of lepton flavour universality in B→ Dℓνℓ decays

© 2019, The Author(s).Radiative corrections to B→ Dℓνℓ decays may have an impact on predictions and measurements of the lepton flavour universality observables R(D+) and R(D). In this paper, a comparison between recent calculations of the effect of soft-photon corrections on R(D+) and R(D) , and corrections generated by the widely used package Photos is given. The impact of long-distance Coulomb interactions, which are not simulated in Photos, is discussed. Furthermore, the effect of high-energy photon emission is studied through pseudo-experiments in an LHCb-like environment. It is found that over- or underestimating these emissions can cause a bias on R(D) as high as 7%. However, this bias depends on individual analyses, and future high precision measurements require an accurate evaluation of these QED corrections.